This invention relates to pyridazinedione compounds useful in the treatment of neurological disorders generally in mammals such as man. More specifically, the compounds are useful in the treatment of strokes and/or other neuro-degenerative disorders such as hypoglycemia, cerebral palsy, transient cerebral ischemic attack, perinatal asphyxia, epilepsy, psychosis, Huntington""s chorea, amyotrophic lateral sclerosis, Alzheimer""s disease, Parkinson""s disease, Olivo-pontocerebellar atrophy, viral-induced neurodegeneration such as in acquired immunodeficiency syndrome and its associated dementia, anoxia such as from drowning, spinal cord and brain trauma, and chronic pain, for the prevention of drug and alcohol withdrawal symptoms, and for the inhibition of tolerance and dependence to opiate analgesics. The invention particularly relates to novel pyridazinedione compounds useful in reducing neurological degeneration such as can be induced by a stroke and the associated functional impairment which can result. Treatment using a compound of the invention can be remedial or therapeutic as by administering a compound following an ischemic event to mitigate the effects of that event. Treatment can also be prophylactic or prospective by administering a compound in anticipation that an ischemic event may occur, for example in a patient who is prone to stroke.
It is known that ischemic events can trigger a dramatic increase in extracellular concentrations of the excitatory amino acids glutamate and aspartate which can, in turn, cause prolonged neuronal excitation leading to a massive influx of calcium from extracellular to intracellular sites in brain neural cells. A calcium overload can thereby be created which leads to a cascade of events leading to cell catabolism and eventually resulting in cell death. The N-methyl-D-aspartate (NMDA) receptor complex is believed to play a significant role in the cascade of events leading to cell necrosis following an ischemic event.
EPO publication number 0 516 297 A1 describes certain pyridazinediones. In addition, the compounds (1) thieno[2xe2x80x2,3xe2x80x2:5,6]pyrido[2,3-d]pyridazine-5,8,9(4H,6H,7H)-trione and (2) thieno[3xe2x80x2,2xe2x80x2:5,6]pyrido[2,3-d]pyrid-azine-4,5,8(6H,7H,9H)-trione are know, for example from J. Heterocyclic Chem., 28, 205, (1991).
Other pyridazinedione compounds are known from, for example, Beilstein""s Handbuch der Organischen Chemie; Godard et. al., Bull. Soc. Chim. Fr., 1588, (1972); and Reid et. al., Chem. Ber., 85, 204, (1952).
Compounds of the present invention relate to novel 2-substituted pyridazinediones or tautomers thereof as shown in formulae I, Ia, Ib, Ic and Id, below, with the variables as recited hereinafter.
The compounds provided by this invention are useful in a variety of neurodegenerative disorders because they function as excitatory amino acid antagonists. They may do so indirectly, via allosteric modulation of the glutamate binding site, or by specifically by acting as antagonists of the strychnine-insensitive glycine receptor on the NMDA receptor complex. They may also do so directly, by binding to the glutamate site itself on the NMDA receptor complex.
The present invention relates to a compound of formula I: 
or pharmaceutically-acceptable salts thereof, wherein:
ring A is chosen from an ortho fused aromatic or hetero-aromatic five- or six-membered ring selected from phenyl, pyridyl, furyl, pyrrolyl or thienyl substituted at 0, 1, 2, 3 or 4 ring carbon atoms with R1;
R1 at each occurrence is independently selected from halo, (C1-C4)alkyl, NO2, CN, perfluoro(C1-C3)alkyl, OH, Oxe2x80x94CF3, (C2-C4)alkenyl, (C2-C4)alkynyl, Oxe2x80x94(C1-C4)alkyl, NRxe2x80x2Rxe2x80x3, SOmRxe2x80x2 where m is 0, 1 or 2, SOmNRxe2x80x2Rxe2x80x3, a heterocyclic group, NRxe2x80x2CORxe2x80x3, CORxe2x80x3, NRxe2x80x2CO2Rxe2x80x3, CO2Rxe2x80x2 and CONRxe2x80x2Rxe2x80x3;
R2 is selected from a cycloalkyl moiety of 3-7 carbon atoms and xe2x80x94CHR3(CH2)nL where R3 is selected from (C1-C6)alkyl, (C0-C6)alkylCF3 and CO2(C0-C6)alkyl;
n is selected from 0-6;
L is selected from halo, OH, CF3, (C3-C6)cycloalkyl, Oxe2x80x94(C1-C4)alkyl, Oxe2x80x94(C1-C4)alkylaryl, (C1-C4)alkylCOORxe2x80x2, Oxe2x80x94CORxe2x80x2, SOmRxe2x80x2, SOmNRxe2x80x2Rxe2x80x3, NRxe2x80x2CORxe2x80x3, NRxe2x80x2CO2Rxe2x80x3, NRCONRxe2x80x2Rxe2x80x3, CO2Rxe2x80x2, CONRRxe2x80x2, NRxe2x80x2Rxe2x80x3 and W; where
W is selected from phenyl or benz derivatives thereof substituted with 0, 1, 2, 3 or 4 groups selected from OH, halo, NO2, CN, CF3, (C1-C4)alkyl, Oxe2x80x94(C1-C4)alkyl, Oxe2x80x94(C2-C4)alkenyl, Oxe2x80x94(C2-C4)alkynyl, Oxe2x80x94(C0-C6)alkylphenyl, (C1-C4)alkylCF3, NH(CO)Rxe2x80x2, NRxe2x80x2Rxe2x80x3, CO2Rxe2x80x2, CONRxe2x80x2Rxe2x80x3, SOmRxe2x80x2, SO2NRxe2x80x2Rxe2x80x3, Oxe2x80x94(C1-C6)alkyloxy(C1-C6)alkyl, Oxe2x80x94(C1-C6)alkylOH, Oxe2x80x94(C1-C6)alkyl-O which forms a cyclic ring attached to a phenyl ring in an ortho manner, aryloxy(C1-C4)alkyloxy(C1-C4)alkyl, Oxe2x80x94(C1-C6)alkyloxy(C1-C6)alkyloxy(C1-C6)alkyl, Oxe2x80x94(C1-C6)alkyloxy(C1-C6)alkyl-OH, Oxe2x80x94(C1-C6)alkylNRxe2x80x2Rxe2x80x3, NRxe2x80x2(C1-C6)alkylNRxe2x80x2Rxe2x80x3, (C1-C6)alkylNRxe2x80x2Rxe2x80x3, O-perfluoro(C1-C4)alkyl, perfluoro(C1-C4)alkyl, NRxe2x80x2(C1-C6)alkyloxy, NRxe2x80x2(C1-C6)alkylhydroxy, (C1-C4)alkyloxy(C1-C4)alkyl, Oxe2x80x94(C1-C4)alkylCOORxe2x80x2, (C1-C4)alkyl)NRxe2x80x2Rxe2x80x3, (C1-C4)alkylORxe2x80x2, NRxe2x80x2(CH2)qCOORxe2x80x2 wherein q is 1-4, S(O)m(C1-C4)alkyloxy(C1-C4)alkyl, S(O)m(C1-C4)alkyloxy(C1-C4)alkyloxy(C1-C4)alkyl, NRxe2x80x2(C1-C4)alkyloxy(C1-C4)alkyl and NRxe2x80x2(C1-C4)alkyloxy(C1-C4)alkyloxy(C1-C4)alkyl; or
W is a heterocycle selected from a five-, six-, or seven-membered heterocyclic ring containing 1, 2, or 3 heteroatoms chosen from O, N, or S, or aryl or heteroaryl benz derivatives thereof, wherein said heterocycle is substituted at a carbon or nitrogen atom with 0 or 1 R or Rxe2x80x2 moieties, or a carbon atom on said heterocycle is disubstituted to form a C5-C7 spiral group, or a carbon atom or sulfur atom on said heterocycle is substituted with 0 or 1 oxygen moieties to form a carbonyl group or SOm group respectively; wherein said heterocycle may be selected from, 2-pyrrolidinone, piperazine, oxazolidone, 2,5-oxazolidinedione, 2,4-imidazolidinedione, 2,4-thiazolidinedione, succinimide or aryl or benz or heteroarylbenz derivatives thereof selected from 3,4-pyridinedicarboximide, -1-pthalimido, isatoic anhydride, orthobenzoic-sulfimide substituted with 0, 1, 2 or 3 alkyl or aromatic substituents selected from halo, OH, phenyl, CF3, CF3, NO2, CN, NH2, SOmRxe2x80x2, NH(C1-C4)alkyl, (C1-C6)alkyl, (C1-C6)alkoxy and N(C1-C4)alkyl2; with the proviso that a heterocyclic nitrogen may not be attached to a nitrogen of the tricyclic ring system of formula I; or
W is a heteroaryl selected from aromatic species and benz derivatives thereof selected from pyridyl, thienyl, furanyl, heteroaryl groups containing two heteroatoms selected from N, O and S, pyrazole, imidazole, isoxazole, oxazole, thiazole, isothiazole, oxidized versions thereof selected from SOm, pyridazine, pyrimidine, pyrazine, heteroaryl groups containing three heteroatoms chosen from N, O or S, triazole, oxadiazole, triazine, heteroaryl groups containing four heteroatoms chosen from N, O or S, and tetrazole, wherein said heteroaryl is substituted at 0 or 1 nitrogen atoms with substituents are selected from OH, (C1-C6)alkoxy, halo, CN and R, where said heteroaryl group is attached to xe2x80x94(CH2)n via a carbon atom or a heteroatom of the heteroaryl group; wherein
R is selected from H or (C1-C4)alkyl;
Rxe2x80x2 and Rxe2x80x3 are independently selected at each occurrence from H, (C1-C6)alkyl, (C2-C4)alkenyl, (C2-C4)alkynyl, cyclo(C3-C6)alkyl, (C0-C4)alkylphenyl, (C0-C4)alkylaryl, (C0-C4)alkylheterocycle and (C0-C4)alkylheteroaryl wherein phenyl, heterocycle and heteroaryl are as defined above and any phenyl, heterocycle, aryl or heteroaryl of Rxe2x80x2 or Rxe2x80x3 is substituted with 0, 1, 2 or 3 groups selected from halo, (C1-C4)alkyl, Oxe2x80x94(C1-C4)alkyl, (C2-C4)alkenyl, (C2-C4)alkynyl, cyclo(C3-C6)alkyl, perfluoro(C1-C3)alkyl, phenyl, NO2, CN, CF3, CF3, OH, Oxe2x80x94(C1-C4)alkyl, NR2, SOmR, SO2NR2, NRCOR, COR, NRCO2R, CO2R, or CONR2 and NNxe2x80x2xe2x80x94(CH2)pxe2x80x94Oxe2x80x94(CH2)pxe2x80x94 where p is chosen from 1-3;
Z is selected from oxo, OH, H, (C1-C6)alkyl and (C1-C6)alkylaryl wherein aryl is substituted with 0, 1, 2 or 3 substituents selected from halogen, (C1-C6)alkyl or other typical aromatic substituents;
R7 is selected from H or C(O)R8 wherein R8 is selected from (C1-C12)alkyl, (C2-C12)alkenyl and (C2-C12)alkynyl either substituted with 0, 1 or 2 substituents selected from: CN, OR9, COR9, COOR9, NR92, CONR92, N(NR9)2, N(CONR9)2, N(COONR9)2 and CONR92 in which the NR92 group is a saturated 4- to 7-membered ring, wherein R9 is selected from hydrogen, (C1-C4)alkyl, pyridyl, pyridyl(C1-C12)alkyl, phenyl and phenyl(C1-C4)alkyl, where phenyl rings of R9-groups are substituted with 0, 1, 2 or 3 substituents selected from halo, amino, hydroxy, cyano, nitro, (C1-C4)alkyl, and (C1-C4)alkoxy;
xe2x80x9c . . . xe2x80x9d indicates that a Cxe2x80x94C or Cxe2x80x94N double-bond is optionally present where chemically possible;
a bond illustrated by wavy line indicates that a designated group may be positioned at different locations.
The N-2 substituted derivatives recited above are readily prepared by reacting the appropriate BOC-protected xe2x80x94CHR3(CH2)nL (as R2) hydrazine as shown generally below with the appropriate 2-pyrrolidinocarbamide-3-carboxylic acid precursor. The general reaction between the R2-substituted hydrazine and the 2-pyrrolidinocarbamide-3-carboxylic acid, reacted with DCC, can be used to selectively produce the N-2 R2 substituted pyridazine quinoline dione (hereinafter xe2x80x9cPQDxe2x80x9d) derivative wherein R2 may be chosen from any of the groups recited above in the definition of R2.
The present invention preferably relates to compounds of formulae Ia, Ib, Ic or Id: 
and pharmaceutically-acceptable salts and tautomers thereof, wherein:
R1, R2, R3, W, R Rxe2x80x2, Rxe2x80x3, Z and R7 are as heretofore defined.
Preferred compounds within the ambit of Formula Ia: 
are those wherein:
R1 is selected from halo, (C1-C4)alkyl and NO2;
R2 is selected from a cycloalkyl moiety of 5-7 carbon atoms, or R2 is selected from a group of the Formulae R2A and R2B
wherein:
n is chosen from 0, 1 or 2;
R4 is selected from (C1-C3)alkyl or (C0-C3)alkylphenyl wherein said phenyl moiety is substituted with 0, 1, 2, 3, 4 or 5 J moieties where J at each occurrence is selected from halogen, (C1-C4)alkyl, NO2, CN, perfluoro(C1-C3)alkyl, OH, CF3, (C2-C4)alkenyl, (C2-C4)alkynyl, or Oxe2x80x94(C1-C4)alkyl;
R5 is phenyl wherein the phenyl group is substituted with 0, 1, 2, 3, 4 or 5 J moieties;
R6 is chosen from hydrogen and (C1-C3)alkyl, and
R7 is selected from hydrogen and C(O)(C1-C3)alkyl.
Preferably, the present invention relates to compounds of formula Ia: 
or pharmaceutically-acceptable salts thereof wherein the ring A is unsubstituted or substituted phenyl and is selected from phenyl, 7-chlorophenyl, 7,9-dichlorophenyl, 7-chloro-9-methylphenyl, 7-methyl-9-chlorophenyl, 7,9-dimethylphenyl, 7-chloro-8-nitrophenyl, 7,9-dichloro-8-nitrophenyl, 7-chloro-9-ethylphenyl wherein the numeric designations refer to the position on the pyridazino quinoline ring system; R2 is selected from cyclohexyl, alpha-methylbenzyl, 1-methylbutyl, 1-(phenylcarbamoyl)ethyl, alpha-methylphenethyl or 1,3-di-methylbutyl, and R7 is selected from H or acetyl.
When R7 is acetyl, the compounds may act as a pro-drug and hydrolyze under physiological conditions to the active parent compound or may be active per se as the mono-acetylated derivative.
The preferred group for R5 s phenyl; and for R6 is methyl or hydrogen. The preferred group for R4 is a (C3-C6)-straight or -branched-chain hydrocarbon (depending upon the value for n) or a phenyl ring (e.g. Oxe2x80x94(C3-C6)alkylphenyl).
Particularly preferred compounds of the Formula Ia, above, are those wherein: R1 is a halo mono-substituent; R2 is cyclohexyl, or has the Formula R2A or R2B wherein R4 is chosen from (C1-C3)alkyl or unsubstituted (C1-C3)alkylphenyl; R5 is unsubstituted phenyl; R6 is hydrogen or (C1-C3)alkyl and R7 is hydrogen.
Especially particularly preferred compounds of the Formula Ia above are those wherein: R1 is a chloro mono-substituent, most preferrably 7-chloro; R2 is cyclohexyl, or has the Formula R2A or R2B wherein R4 is methyl, isopropyl, or phenyl; R5 is phenyl; R6 is hydrogen or methyl; R3 is methyl, trifluoromethyl, CO2H or CO2CH3, and R7 is hydrogen.
Preferred species of the Formula Ia are selected from
7-chloro-4-hydroxy-2-[1-(N-phenylcarbamoyl)ethyl]-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-cyclohexyl-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-(1-methylbenzyl)-1,2,5,10-tetra-hydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-(1-methylbutyl)-1,2,5,10-tetra-hydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-(1-methyl-2-phenylethyl)-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-(1,3-dimethylbutyl)-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-[(R)-1-(methyloxy-carbonyl)ethyl]-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-[1-(methyloxycarbonyl)benzyl]-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-[1-(N-phenyl-N-methylcarbamoyl)ethyl]-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-[1-methyl-2-(N-phenylcarbamoyl)-ethyl]-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-[1-methyl-2-(N-phenyl-N-methyl-carbamoyl)ethyl]1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-(1-trifluoromethylbenzyl)-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione,
7-chloro-4-hydroxy-2-(1-carboxybenzyl)-1,2,5,10-tetra-hydropyridazino[4,5-b]quinoline-1,10-dione, and
7-chloro-4-hydroxy-2-[(R)-1-carboxyethyl]-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione.
The present invention also relates to a pharmaceutical composition comprising a compound of formula I, Ia, Ib, Ic or Id with the variables recited above and a pharmaceutically-acceptable excipient or diluent.
The invention further relates to a method for the treatment of neurological disorders comprising administering to a patient in need of such treatment an effective amount of a compound of the formula I, Ia, Ib, Ic or Id.
The present invention also relates to a method of treating or preventing ischemic damage in a patient in need of such treatment comprising administering a pharmaceutically-effective amount of a compound of formula I, Ia, Ib, Ic or Id with the variables as recited above to said patient.
The invention further relates to a method of treating or preventing neurological damage associated with excitatory amino acids in a patient in need of such treatment comprising administering a pharmaceutically-effective amount of a compound of formula I, Ia, Ib, Ic or Id to said patient.
The invention also relates to a method of treating stroke or epileptic convulsions or diseases or disorders associated with excessive calcium influx in the brain caused by excitatory amino acids comprising administering to a patient in need of treatment thereof a pharmaceutically-effective amount of a compound of formula I, Ia, Ib, Ic or Id.
The invention further relates to a process for producing a compound of formula I, Ia, Ib, Ic or Id, comprising: treating any of the compounds of formula Ia with a reducing agent under suitable conditions to form a compound of formula Ib and further treating a compound of formula Ib with a reducing agent under the appropriate conditions to form a compound of formula Ic.
The invention further relates to a process for producing a compound of formula I, Ia, Ib, Ic or Id according to certain steps recited herein, or as shown in the examples, wherein the compounds are selected from:
(a) 7-chloro-4-hydroxy-2-[1-(phenylcarbamoyl)ethyl]-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione;
(b) 7-chloro-4-hydroxy-2-cyclohexyl-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione;
(c) 7-chloro-4-hydroxy-2-(alpha-methylbenzyl)-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione;
(d) 7-chloro-4-hydroxy-2-(1-methylbutyl)-1,2,5,10-tetra-hydropyridazino[4,5-b]quinoline-1,10-dione;
(e) 7-chloro-4-hydroxy-2-(alpha-methylphenethyl)-1,2,5,10-tetrahydropyridazino[4,5-b]quinoline-1,10-dione; and
(f) 7-chloro-4-hydroxy-2-(1,3-dimethylbutyl)1,2,5,10-tetra-hydropyridazino [4,5-b]quinoline-1,10-dione.
The invention further relates to a process for producing a compound of the Formula I which comprises:
(a) reacting a compound of the Formula IV: 
with a hydrazine of the formula: 
to produce a compound of the Formula II 
and (b) reacting said compound of the Formula II with an acid to afford the compounds of the Formula I.
The invention also relates to the use of a compound of formula I, Ia, Ib, Ic or Id in medical treatments for diseases or disorders associated with excitatory amino acids.
The invention further relates to the use of a compound of the formula I, Ia, Ib, Ic or Id for the preparation of a medicament for the treatment of neurological disorders.
The invention also relates to the use of a compound of formula I, Ia, Ib, Ic or Id for the treatment or prevention of stroke or epileptic convulsions or disorders or conditions associated with excessive influx of calcium ions in the brain.
None of the compounds recited herein have produced any untoward side effects.
The present invention also relates to compounds which are useful as key intermediates in the production of glycine receptor antagonists. Key intermediates include 3-carboxylic acid quinoline-2-pyrrolidineamide compounds which are utilized to react with BOC-protected substituted hydrazines to form, after coupling with dicyclohexyldiimide or diisopropyldiimide or 1-cyclohexyl-3-(2-morpholinyl-ethyl)-carbodiimide in a polar solvent such as THF, methanol, diethylether, dioxane, CH2Cl2, CH3CN or DMF, and an acid (e.g. CH3SO3H) to produce a-pyrrolidinocarbamide-3-carboxylic acid-N-1 R2-substituted hydrazide, which after deprotection or removal of BOC or other bulk N-protection groups, leads selectively to the N-2 substituted PQD. (See Scheme 1, formula II and III) wherein R2 is defined as recited herein. The pyrrolidine may be substituted with an equivalent amine which produces an amide with limited steric hindrance and which acts as an appropriate leaving group. 
The present invention also relates to pharmaceutical compositions containing a preferred compound of formula Ia as shown above and a pharmaceutically-acceptable carrier.
It will be appreciated that the formulae described herein can be drawn in various tautomeric and positional isomeric forms, as discussed below. The present invention includes such alternate forms unless otherwise indicated, also includes salts thereof, especially the pharmaceutically-acceptable addition salts.
It will be appreciated that some of the compounds disclosed herein can exist and be drawn in various true tautomeric forms (i.e., imine to enamine conversion in the center ring).
It will further be appreciated by those skilled in the art that certain compounds of formula I may contain an asymmetrically substituted carbon atom, and accordingly may exist in, and be isolated in, optically-active and racemic forms. Some compounds may exhibit polymorphism. It is to be understood that the present invention encompasses any racemic, optically-active, polymorphic or stereoisomeric form, or mixtures thereof, which form possesses properties useful in the treatment of neurodegenerative disorders, it being well known in the art how to prepare optically-active forms (for example, by resolution of the racemic form or by synthesis from optically-active starting materials) and how to determine neuroprotective properties by the standard tests described hereinafter.
The invention further provides a method for the treatment of neurological disorders, comprising administering to a mammal in need of such treatment an effective amount of a compound according to the invention as defined above, or a pharmaceutically-acceptable salt thereof, or a composition as defined above. The invention also encompasses a method of antagonizing an NMDA receptor in mammals comprising administering a pharmaceutically-effective amount of the compound or its salt as claimed herein or a pharmaceutical composition as recited herein to a patient in need of treatment thereof. The preferred therapeutic treatment area is prevention and/or treatment of stroke. A pharmaceutically-effective amount of a compound as claimed and disclosed in the present invention may be administered immediately after an ischemic event to prevent cell damage and/or cell death.
The present invention is also directed to a method of preventing and/or treating damage induced by the excitatory amino acids such as L-glutamate. The invention also relates to a method of preventing the excessive influx of calcium ions in central neurons. The invention relates to a method of preventing ischemic neuronal injury following transient global ischemia and a method of reducing infarct volume following focal ischemic insults by treating a patient in need of treatment thereof with a pharmaceutically-effective amount of a compound of formula Ia wherein the variables for R1 and R2 are as defined herein. In addition to being useful in the treatment of acute stroke patients, the compounds and compositions of the invention may be extremely beneficial in preventing neurological morbidity during cardiac resuscitation or administered as cerebral prophylatics during high-risk surgery.
In this specification the terms xe2x80x9calkylxe2x80x9d and xe2x80x9calkoxyxe2x80x9d include both straight and branched chain radicals, but it is to be understood that references to individual radicals such as xe2x80x9cpropylxe2x80x9d or xe2x80x9cpropoxyxe2x80x9d embrace only the straight chain (xe2x80x9cnormalxe2x80x9d) radical, branched chain isomers such as xe2x80x9cisopropylxe2x80x9d or xe2x80x9cisopropoxyxe2x80x9d being referred to specifically.
The term xe2x80x9chaloxe2x80x9d is inclusive of fluoro, chloro, bromo, and iodo unless noted otherwise.
The term cycloalkyl moiety of 3-7 carbon atoms means cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cyclo-heptyl, preferably cyclohexyl.
Particular values of (C1-C3)alkyl include methyl, ethyl, propyl, isopropyl.
Particular values of (C2-C4)alkyl containing a double or triple bond include vinyl, 2-propenyl (i.e. allyl), 2-propynyl, (i.e. propargyl), 2-butenyl, and 3-butenyl.
Particular values of (C1-C4)alkoxy include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, and t-butoxy.
Particular values of (C1-C6)alkyl include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, isohexyl.
Particular values of (C2-C6)alkyl containing a double or triple bond include vinyl, 2-propenyl (e.g. allyl), 2-propynyl, (e.g. propargyl), but-2-enyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 4-pentynyl, 5-hexenyl, 5-hexynyl.
Particular values of phenyl substituted with from 0-4 substituents may include but are not limited to phenyl; 2-, 3-, and 4-halophenyl; 2-, 3-, and 4-aminophenyl; 2-, 3-, and 4-hydroxyphenyl; 2-, 3-, and 4-cyanophenyl;2-, 3-, and 4-nitrophenyl; 2-, 3-, and 4-methylphenyl; 2-, 3-, and 4-ethylphenyl; 2-, 3-, and 4-propylphenyl; 2,3 or 4-isopropylphenyl: 2-, 3-, and 4-methoxyphenyl; 2-, 3-, and 4-ethoxyphenyl; 2-, 3-, and 4-propoxyphenyl; and 3,5-dihalophenyl, 3-halo-4-hydroxyphenyl, and 3,5-dihalo-4-hydroxyphenyl and phenyl substituted at 1, 2 or 3 carbon atoms with methoxyethyloxy, methoxyethyloxyethyloxy, N,N-dimethylethyloxy, and N,N-dimethylethylaminyl; 3,4-dimethoxy; 3,4-dihydroxy; 3,5-dimethoxy; 3,5-dihydroxy or 2,3,4-SMe or 2,3,4-SH and further includes groups selected from 4-(SO2CH3)phenyl, 2-methyl-4-chlorophenyl, 2,4-dihalophenyl, 4-tetrazolylphenyl, 3,5-trifluoromethyl-phenyl, 2,4-dimethylphenyl, 3-halo-4-methylphenyl, 4-trifluoromethylphenyl, 3,4-dimethylphenyl, 2-methyl-4-methoxyphenyl, 2-methoxy-4-halophenyl, 2-methyl-4-hydroxyphenyl, 2,3-dimethylphenyl, 2,4-dimethoxyphenyl, 2,5-dimethoxyphenyl, 2,5-dimethylphenyl, 4-benyloxyphenyl, 4-ethoxyphenyl, 2,5-dihydroxyphenyl, 4-vinylphenyl, 2,5-dihalophenyl, 2-methyl-4-fluorophenyl, and 2-, 3- and 4-(CONRxe2x80x2Rxe2x80x3)phenyl.
Particular values of phenyl(C1-C4)alkyl substituted with from 0-4 substituents may include benzyl, phenylethyl, phenylpropyl, phenylbutyl, 2-, 3-, 4 and 5-halobenzyl; 2-, 3- and 4-CF3-benzyl; 2-, 3-, and 4-aminobenzyl; 2-, 3-, and 4-cyanobenzyl; 2-, 3-, and 4-methylbenzyl; 2-, 3-, and 4-methylbenzyl; 2-, 3-, and 4-ethylbenzyl; 2-, 3-, and 4-propylbenzyl; 2-, 3-, and 4-hydroxybenzyl; 2-, 3-, and 4-methoxybenzyl: 2-, 3-, and 4-ethoxybenzyl; 2-, 3-, and 4-propoxybenzyl; 3,5-dihalobenzyl, 3-halo-4-hydroxybenzyl, 3,5-diCF3benzyl, 3,5-dihalo-4-hydroxybenzyl, 2,3,4,5,6-pentahalobenzyl; and phenyl(C1-C4)alkyl substituted on the phenyl with methoxyethyloxy, methoxyethyloxyethyloxy, N,N-dimethyl-ethyloxy, and N,N-dimethylethylaminyl; 3,4-dimethoxy; 3,4-dihydroxy; 3,5-dimethoxy; 3,5-dihydroxy or 2,3,4-SMe or 2,3,4-SH.
More particular values of halo include chloro and bromo.
More particular values of perfluoro(C1-C3)alkyl include trifluoromethyl and pentafluoroethyl.
More particular values of 4- to 7-membered rings containing nitrogen include piperidino, piperazinyl and pyrrolidinyl.
More particular values of (C1-C3)alkyl substituted with a trifluoromethyl group include trifluoromethylmethyl and 2-trifluoromethylethyl.
More particular values of phenyl substituted with from 0-3 substituents may include phenyl; 2- and 4-halophenyl; 2- and 4-aminophenyl; 2-, 3- and 4-hydroxyphenyl; 2-, 3- and 4-methoxyphenyl, 2,4-dihalophenyl, 3,5-dihalophenyl, 2,6-dihalo-4-hydroxyphenyl, 2-halo-4-methylphenyl, 2-methoxy-4-methylphenyl, 2-methyl-4-methoxyphenyl, 3-hydroxy-4-methyl phenyl, 2-hydroxy-4-methylphenyl, 2-methyl4-chlorophenyl, 2,4-dimethylphenyl, 3,4-dimethoxyphenyl, 2-methyl-4-methoxyphenyl, 3,4-dihydroxyphenyl and 2,4-dimethylphenyl and includes those values specifically exemplified in the examples.
More particular values of phenyl(C1-C4)alkyl substituted with 0-3 substituents include benzyl; phenylethyl; 2- and 4-halobenzyl; 2- and 4-cyanobenzyl; 2- and 4-nitrobenzyl; 2- and 4-methoxybenzyl, 2,4-dihalobenzyl, 3,5-dihalobenzyl; and 2,6-dihalo-4-hydroxybenzyl. The corresponding phenethyl isomers are also included.
Of course, because of the convenient and easy preparation of the starting Nxe2x80x2xe2x80x94R2 substituted BOC protected hydrazines, the above compounds are non-limiting and include any of the compounds within the generic scope as recited previously.
Pyridazinediones of formula I (or other formulae as recited herein) can be made by processes which include processes known in the chemical arts for the production of structurally analogous compounds. The preparation of compounds wherein Z is H on certain starting materials described herein, can be effected by chlorinating the hydroxy group of the dialkyl 4-OH-quinoline-2,3-dicarboxylate (starting material) using phosphorous oxychloride. This chlorine is then reduced using tetrakistriphenylphosphine Pd(O) and sodium formate to provide dimethylquinoline-2,3-dicarboxylate which is then processed through the remaining chemical steps (i.e., adding the hydrazine etc.) The processes for the manufacture of a starting pyridazinedione of formula I as defined above, are provided to show the preparation of the preferred starting materials utilized in the present invention and are illustrated by the following procedures in which the meanings of generic radicals are as given above unless otherwise qualified.
To obtain a compound of formula I via a process as described herein such a process is effected generally according to the procedure described in Scheme 1 or as specifically exemplified in non-limiting examples 1-14. A 2-pyrrolidinocarbamide-quinoline-3-carboxylic acid is prepared from hydrolysis of the corresponding 3-methyl-ester which is prepared by reacting the corresponding 3-carbomethoxyquinoline-2-carboxylic acid with dicyclohexylcarbodimide, or other appropriate diimide coupling-reagent such as diisopropyl carbodiimide and pyrrolidine. The 2-pyrrolidinocarbamide-quinoline-3-carboxylic acid is reacted with an N-t-butoxycarbonyl-Nxe2x80x2-2-CHR3(CH2)nL-hydrazine (where L can be xe2x80x94R4 or xe2x80x94C(O)NR5R6 and n=0-4) to obtain a key intermediate hydrazide which is cyclized in CH3SO3H/THF, or an equivalent solvent, to selectively form a 2-substituted xe2x80x94(CHR3)(CH2)n aryl or xe2x80x94(CHR3)(CH2)n-alkylaryl-PQD or a xe2x80x94(CHR3)(CH2)n substituted alkyl-PQD.
Hydrazines may be prepared by the reaction of t-butylcarbazate and the desired C1-C4 alkylaryl or a substituted alkyl aryl or an alkoxy alkyl compound wherein the terminal alkyl carbon has a suitable leaving group selected from halo (X) or triflate in a solvent such as DMF, CH2Cl2 or CH3CN, or equivalent, and a base such as NEt3. Additionally, other groups which may readily react with t-butylcarbazate to form a starting disubstituted hydrazine t-butylO(CO)xe2x80x94Nxe2x80x94Nxe2x80x94R2 include any alkylaryl, aryloxyalkyl, alkyloxyalkyl, alkyloxyalkyloxy or alkylheteroaryl recited herein wherein the alkyl group has a suitable leaving group. Further, for n=0-4, the desired hydrazines may be obtained by reaction of a suitable aryl or substituted aryl aldehyde or substituted alkylaldehyde with t-butylcarbazate in refluxing hexanes or an equivalent organic solvent to form the corresponding imine which is then reduced to the hydrazine compound with a reducing agent (e.g. BH3 or LiAlH3).
This process may generally be utilized to selectively form a compound of formula I. t-Butylcarbazate is commercially available and the R2-substituted t-butyl-carbonate-hydrazines are readily prepared. As described in the examples, there are at least three ways to prepare the starting substituted hydrazines;-methods X, Y and Z (See Scheme 2). As is readily apparent from Scheme 2, the starting halides, aldehydes or alcohol are easily prepared or are commercially available. 
A compound of formula I wherein L is a heterocyclic moiety such as a 4-(C1-C6)substituted piperazine or 4-arylsubstituted piperazine or a phthalimido or another commercially available nucleophilic heterocycle, may be formed by reacting the heterocyclic nucleophilic species with a 2-halo(CH2)nCR3alkyl-pyridazino[4,5-b]quinoline of formula I, which is prepared from the corresponding hydroxy species. As the following examples will show, compounds within the scope of the present invention are prepared by a variety of chemical synthetic steps or procedures. Compounds of formula I wherein Z is (C1-C6)alkyl or (C1-C6)alkylaryl may be prepared from the corresponding compound of formula I with Z as oxo by alkyl or alkylaryl addition to the central-ring carbonyl of the PQD. Grignard reactions using ZMgX or coupling systems with alkyl lithium anions (e.g. ZLi or ZM) or a Wittig reaction using Ph3P-C(RRxe2x80x2) may be utilized to form a precursor to a compound of formula I which is subsequently reduced or modified and reduced to form a compound of formula I wherein Z is alkyl or alkylaryl.
In the case of alkylation or benzylation of the B-ring carbonyl, it may be necessary to perform the reaction on a pre-coupled precusor which is also nitrogen-protected. This would avoid unselective alkylation at the C-ring carbonyls. However, it may also be possible to protect the C-ring carbonyl(s) before alkylating (with ZM) the B-ring carbonyl.
In general, Schemes 1 and 2 describe how some of the compounds within the scope of the present invention or intermediates are prepared. The preferred compounds are those of formula Ia. The preferred process for producing compounds of formula Ia involves preparing an intermediate PQD of formula II or III (Scheme 1) which is then cyclized to a compound of formula Ia (R7=H). This compound may be reduced to a compound of formula Ib or Ic under the conditions as described below (see Scheme 1). The preferred reduction conditions involve suspending a compound of formula Ia, prepared as shown in examples 1-6, in an organic solvent such as THF, with subsequent addition of a significant molar excess of trifluoroacetic acid. This suspension is cooled to about 0xc2x0 C. and sodium borohydride is added in molar excess (5xc3x97 or less). The reduction is then allowed to proceed at 0xc2x0 C. for about 15 minutes and then the suspension is warmed to room temperature and stirred for about 3 hours. Upon work-up and after triturating and filtering (2xc3x97), the title compounds are readily obtained. The preferred group for Z on a compound of formula I is oxygen. Z, in a compound of formula I, may also be hydrogen, OH SH or NHR or as otherwise described herein. Key intermediates are shown in Schemes 1 and 2, or described in the text.
The examples are provided for illustrative purposes and are not to be interpreted as limiting the scope of the present invention. A key process for selectively producing N-2-(CHR3)(CH2)naryl or xe2x80x94(CHR3)(CH2)nheteroaryl substituted alkyl or other species prepared from any N-2 intermediates, involves the initial production of a 2-pyrrolidinoamido substituted quinoline which is formed from the corresponding 2-carboxy-3-carboalkoxy quinoline. This compound, or analogous compounds (e.g. with groups equivalent to pyrrolidinoamido), is hydrolyzed to form the corresponding 2-pyrrolidinoamido-3-carboxy quinoline of formula IV (Scheme 1), which is then coupled with the selected R2xe2x80x94Nxe2x80x94Nxe2x80x94C(O)O-t-butyl hydrazine using a selected diimide (e.g. DCC or equivalent) to form a hydrazide intermediate. For example, 2-pyrrolidinoamido-3-carboxylic acid-NR2-N(BOC) hydrazide under the cyclization conditions, forms the N-2 substituted PQD without formation of any N-3 substituted PQD. Further, the alphamethylbenzyl or substituted benzyl compounds described herein are readily and conveniently prepared from the appropriate 2-pyrrolidinoamido-3-carboxylic acid and the N-alphamethylbenzylNxe2x80x2-t-butyl carboxy hydrazine which was actually prepared from the corresponding alkylhalide and t-butyl carbazate. t-Butylcarbazate reacts readily to displace the halide or alcohol such as triflate to form the desired hydrazine.
Another intermediate and glycine receptor antagonist includes N-2-alpha-substituted (C1-C6)alkylaryl PQDs of formula I substituted with a cyano substitutent or substituents. The CN moiety can be further converted to form carboxylic acids, carbonyl halides, esters, amides, or tetrazoles. As indicated previously, anion displacement (nucleophilic displacement) is utilized to produce various heterocyclic compounds or benz or heteroaryl benz derivatives thereof which are glycine receptor antagonists. An N-2 halo(C1-C4)alkyl PQD is reacted with the selected nucleophile (heterocyclic or heteroaryl) to form the corresponding N-2 nucleophile-(C1-C4)alkyl PQD.
If not commercially available, the necessary starting materials for the procedures such as that described above may be made by procedures which are selected from standard organic chemical techniques, techniques which are analogous to the synthesis of known, structurally similar compounds, or techniques which are analogous to the above described procedure or the procedures described in the examples.
Examples of suitable pharmaceutically-acceptable salts are salts formed with bases which form a physiologically acceptable cation, such as alkali metal (especially lithium, sodium and potassium), alkaline earth metal (especially calcium and magnesium), aluminum and ammonium salts, as well as salts made with appropriate organic bases such as choline hydroxide, triethylamine, morpholine, piperidine, ethylenediamine, lysine, ethanolamine, diethanolamine, triethanolamine, N-methyl-D-glucamine (meglumine), arginine, and tris(hydroxymethyl)aminomethane. Choline, meglumine, sodium and potassium salts are preferred. Choline, sodium and potassium salts are especially preferred.
When used to intervene therapeutically following a stroke, a pyridazinedione of formula I, Ia, Ib, Ic or Id generally is administered as an appropriate pharmaceutical composition which comprises a compound according to the invention as defined herein, together with a pharmaceutically-acceptable diluent or carrier, the composition being adapted for the particular route of administration chosen. Such compositions are provided as a further feature of the invention. They may be obtained employing conventional procedures and excipients and binders and may be in a variety of dosage forms. For example, they may be in the form of tablets, capsules, solutions or suspensions for oral administration; in the form of suppositories for rectal administration; in the form of sterile solutions or suspensions for administration by intravenous or intramuscular injection or infusion; and in the form of powders together with pharmaceutically-acceptable inert solid diluents such as lactose for administration by insufflation.
The dose of a compound according to the invention which is administered will necessarily be varied according to principles well known in the art taking account of the route of administration, the severity of the post-ischemic disorder, and the size and age of the patient. In general, a compound of according to the invention will be administered to a warm blooded animal (such as man) so that an effective dose is received, generally a dose in the range of about 0.01 to about 100 mg/kg body weight. For example, if the compound is administered intravenously, it is administered in the range of about 0.01 to about 10 mg/kg body weight. If it is administered orally, it is administered in the range of about 0.5 to about 100 mg/kg body weight.
It will be apparent to those skilled in the art that a compound according to the invention can be co-administered with other therapeutic or prophylactic agents and/or medicaments that are not medically incompatible therewith. In general, representative compounds of the instant invention do not show any indication of significant toxicity in laboratory test animals.
The actions of compounds according to the invention as antagonists at the glycine receptor of the NMDA receptor complex can be shown by one or more standard tests such as the [3H]-glycine binding assay (Test A) and by in vivo tests such as the red nucleus test (Test B) and the Rat Middle Cerebral Artery test (Test C). These tests confirm that compounds of the invention function as NMDA receptor antagonists in vitro and in vivo. Certain compounds of the invention are potent NMDA receptor antagonists.
In the [3H]-glycine binding assay, neuronal synaptic membranes are prepared from adult (about 250 g) male Sprague-Dawley rats. Freshly dissected cortices and hippocampi are homogenized in 0.32 M sucrose (110 mg/mL). Synaptosomes are isolated by centrifugation (1000xc3x97g, 10 min), the supernatant is pelleted (20,000xc3x97g, 20 min) and resuspended in double-distilled water. The suspension was centrifuged for 20 minutes at 8,000xc3x97g. The resulting supernatant and buffy coat are washed twice (48,000xc3x97g, 10 min) and resuspended in double-deionized water. The final pellet is quickly frozen (dry ice/ethanol bath) under double-deionized water and stored at xe2x88x9270xc2x0 C.
On the day of the experiment, thawed synaptic membranes are homogenized with a Brinkmann Polytron (Brinkmann Instruments, Westbury, N.Y.) tissue homogenizer in 50 millimolar tris(hydroxymethyl)aminomethane citrate, pH 7.1. The membranes are incubated with 0.04% Sufact-AMPS X100 (Pierce, Rockford, Ill.) in buffer for 20 minutes at 37xc2x0 C. and washed six times by centrifugation (48,000xc3x97g, 10 min) and resuspended in buffer. The final pellet is homogenized at 200 mg wet weight/mL of the buffer for the binding assay.
For [3H]-glycine binding at the N-methyl-D-aspartate receptor, 20 nanomolar [3H]-glycine (40-60 Ci/mmol, New England Nuclear, Boston, Mass.) is incubated with the membranes suspended in 50 millimolar tris(hydroxymethyl)aminomethane citrate, pH 7.1 for 30 minutes at 4xc2x0 C. Glycine, 1 millimolar, is used to define the nonspecific binding. Bound [3H]-glycine is isolated from free using a Brandel (Biomedical Research and Development Laboratories, Gaithersburg, Md.) cell harvester for vacuum filtration over glass fiber filters (Whatman GF/B from Brandel, Gaithersburg, Md.) presoaked in 0.025% polyethylenimine. The samples retained on the glass fiber filters are rinsed 3 times with a total of 2.5 mL ice cold buffer. Radioactivity is estimated by liquid scintillation counting. IC50 values are obtained from a least-squares regression of a logit-log transformation of the data. Typical IC50 values for compounds of the invention are usually less than 50 microM and are illustrated by the compound of Examples 1-6 (Ex. 1, 2.4xc3x9710xe2x88x927; Ex. 2, 1.2xc3x9710xe2x88x927; Ex. 3, 3.7xc3x9710xe2x88x927; Ex. 4, 2.4xc3x9710xe2x88x927; Ex. 5, 3.0xc3x9710xe2x88x927; Ex. 6, 2.9xc3x9710xe2x88x927 M).
Red Nucleus Test
The purpose of this test is to determine the effects of intravenously administered glycine antagonists on the NMDA-induced excitatory response of red nucleus cells. HA-966 (racemic) and CGP 37849 are reference agents that have been shown active in this test (ID50s of 7.9 and 1.7 mg/kg iv, respectively).
The procedure for the red nucleus test is as follows. Rats are anesthetized with chloral hydrate (400 mg/kg ip) and the femoral vein is catheterized for iv drug administration. Five-barrel micropipettes are stereotaxically positioned in the red nucleus. Typically, three to four of the five barrels are filled as follows: the recording barrel with 2M potassium citrate, the current balancing barrel with 4M NaCl, the drug barrel with 25 mM NMDA, and another drug barrel with 2.5 mM quisqualic acid (QA is only used in selectivity studies). NMDA is iontophoretically applied with an ejection current that is adjusted depending on the sensitivity of each individual red nucleus cell. The NMDA is cycled on and off (usually 30-60 sec. on and 60-120 sec. off) and the firing rate of the cell during each period is recorded. Once the baseline firing rate of the cell has been established, the test drug is administered iv. The effect of the drug on the NMDA-induced excitatory response of the red nucleus cell can be both qualitatively and quantitatively evaluated from the recordings and the raw data accumulated. Compounds of the invention exhibited a antagonist response. For example, the compound of example 4 as the meglumine salt (N=3) had an ID50 of 3.770.
Rat Middle Cerebral Artery Test
Male SHR rats weighing 280-320 g are used for these studies. The method used for permanent middle cerebral artery (MCA) occlusion is as described by Brint et al (1988). Briefly, focal ischemia is produced by occluding first the left common carotid artery and then the left middle cerebral artery just superior to the rhinal fissure. Following occlusions, drugs are administered intravenously via jugular catheter. Twenty-four hours after MCA/common carotid artery occlusion, the animals are sacrificed and their brains quickly removed. Coronal sections of 1 mm thickness are cut using a vibratome and stained with 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) dye. Following staining, necrotic tissue is readily distinguished from the intact brain and the area of infarcted cortex can be traced on an image analyzer. The infarct volume for each section is quantified with an image analyzer, and the total infarct volume is calculated with a program that summed all interval volume. See S. Brint et al. J. Cerebral Blood Flow 8:474-485 (1988). The statistical analysis of the difference between the volume of ischemic damage in the vehicle control and drug-treated animals is analyzed by Student""s t-test. All data are presented as the mean xc2x1S.E. of the mean for n animals. compounds of the invention reduced ischemic damage. For example, the compound of example 4 at an I.V. dose of 20 mgs/kg/hr caused an infarct % volume change of xe2x88x9222%.
The invention will now be illustrated by the following non-limiting examples. In the Examples, unless stated otherwise:
(i) temperatures are given in degrees Celsius (xc2x0 C.); operations were carried out at room or ambient temperature, that is, at a temperature in the range of 18-25xc2x0 C.;
(ii) evaporation of solvent was carried out using a rotary evaporator under reduced pressure (600-4000 Pascals; 4.5-30 mm Hg) with a bath temperature of up to 60xc2x0 C.;
(iii) flash chromatography was carried out on Merck Kieselgel (Art 9385) and column chromatography on Merck Kieselgel 60 (Art 7734); (obtained from E. Merck, Darmstadt, W. Germany); thin layer chromatography (TLC) was carried out on Analtech 0.25 mm silica gel GHLF plates (Art 21521), obtainable from Analtech, Newark, Del., USA;
(iv) in general, the course of reactions was followed by TLC or HPLC and reaction times are given for illustration only;
(v) melting points are uncorrected and (d) indicates decomposition; the melting points given are those obtained for the materials prepared as described; polymorphism may result in isolation of materials with different melting points in some preparations;
(vi) all final products were essentially pure by TLC or HPLC and had satisfactory nuclear magnetic resonance (NMR) spectra (300 MHz 1H NMR in D-DMSO unless otherwise specified) and microanalytical data;
(vii) yields are given for illustration only;
(viii) chemical symbols have their usual meanings; the following abbreviations have also been used: v (volume), w (weight); mp (melting point), L [liter(s)], mL (milliliters), mM (millimoles), g [gram(s)], mg [milligram(s)], min (minutes), h (hour); and
(ix) solvent ratios are given in volume: volume (v/v) terms.
As the examples and in vitro or in vivo results indicate, the present invention or the compounds and glycine receptor antagonists recited herein are useful as in vitro tools for determining relative glycine antagonist properties and as in vivo compounds or compositions which are useful as in vivo tools for determining relative antagonist properties and as compounds or compositions which antagonize the glycine receptor in animals or humans in need of treatment thereof. The present invention, therefore, also relates to a method of in vitro antagonism of a mammalian glycine receptor comprising administering an antagonist effective amount of a compound of formula I, Ia, Ib, Ic or Id. The invention further relates to a method of in vivo antagonism of a mammalian, including human, glycine receptor comprising administering a pharmacologically effective amount of a compound of formula I, Ia, Ib, Ic or Id to a mammal or a human.